Upon the secession of Virginia from the Union in 1861, numerous ships in the Gosport Navy Yard in Norfolk were scuttled to prevent them from falling into the hands of the Confederate States Navy. The Merrimack was salvageable, however, and the Confederates began to restore and improve her for battle. In response, the Union initiated the need for an ironclad warship to counter the Merrimack, re-christened as the Virginia. The Monitor, designed by the Swedish-born inventor John Ericsson, was one of the designs accepted. Innovative in several respects, the ship featured a gun turret rotating a complete 360° as well as a completely underwater hull.

Action came on 8 March 1862 when the Virginia attacked a Union blockading squadron in Hampton Roads, destroying some Union ships. That night, the Monitor came to the rescue, with the two ships engaging one another throughout the following day. Though neither was heavily damaged, the Monitor was successful in preventing the Virginia from gaining any further ground in her attempt to counter the blockade.

The end for the Monitor came later that year, as her design made her highly unseaworthy. She languished in stormy waters and sank off the coast of Cape Hatteras on 31 December 1862.